In a virtual cell network system, a distribute small base station may be overlapped and included with multiple virtual cells by a Central Management Unit (CMU). The virtual cell network system may be a type of a system in which a plurality of distribute small base stations share a plurality of user terminals in a micro cell serviced by one physical space (e.g., a micro cell serviced by a micro base station).
FIG. 1 illustrates a situation in which one terminal is downlink or uplink-connected to a plurality of base stations in a virtual cell network system.
In the existing cellular system, generally, the distance between base stations is wide, and a terminal is usually connected to one base station or is connected to two base stations in a cell boundary area. A random access competitive composition in the cellular system may be defined as a plurality of random access attempts of the terminal for random access resources of one base station. However, when the distance between the base stations is relatively small as shown in the virtual network system of FIG. 1, a situation, in which a terminal existing in a cell boundary is connected to two or more base stations, frequently occurs.
As described above, in a situation in which the terminal is uplink-connected to the plurality of base stations in the virtual cell network system, there is a need to solve a random access collision problem in view of the terminal rather than the base station.